An electronic display device, ideally, displays a color image by a combination of three primary colors, i.e., red, blue, and green. In an actual display device, however, there has been a problem that since unwanted light other than light of the three primary colors (e.g., in a plasma display panel, light with a wavelength of 550 to 600 nm: neon emissions) is also involved in the image, the color purity of the image is degraded. In order to solve such a problem, a display device with a filter having a color correction function has been invented.
It has been known that a squarylium compound is used as a coloring agent for filters of electronic display devices. For example, Japanese Published Unexamined Patent Application No. 2001-192350 discloses a plasma display panel containing a squarylium compound represented by the following formula, etc.

However, the above plasma display panel is not satisfactory in practical use because the light transmittance is insufficient in the wavelength range near 500 nm.